Method of treating waste magnetic tapes and method of manufacturing building material boards using the treated material

ABSTRACT

The present invention provides a method of treating waste magnetic tapes characterized in that waste magnetic tapes such as video tapes and cassette tapes are cut or crushed to a length of 1 to 50 mm, and heated at a temperature of 100° to 200° C. so that they are contracted in the form of curl, and a method of manufacturing building material boards characterized in that waste magnetic tapes such as video tapes and cassette tapes are cut or crushed to a proper size, heated, and then, supplied with a binder and molded under pressure.

TECHNICAL FIELD

The present invention relates to a method of treating waste magnetictapes and to a method of manufacturing building material boards usingthe treated material obtained thereby.

BACKGROUND ART

Although a huge amount of waste magnetic tapes of those such as videotapes and cassette tapes has been disposed of every year, heretofore, amethod of recycling properly such waste tapes has not been found.

DISCLUSIVE OF THE INVENTION

The present invention proposes a method of treating the above-mentionedwaste magnetic tapes and a method of manufacturing building materialboards from the treated material.

SUMMARY OF THE INVENTION

The subject matter of the present invention is both a method of treatingwaste magnetic tapes characterized in that waste magnetic tapes of thosesuch as video tapes and cassette tapes are cut or crushed to a length of1 to 50 mm, preferably 3 to 10 mm, and heated at a temperature of 100°to 200° C., preferably 140° to 170° C. so that they are contracted inthe form of curl, and a method of manufacturing building material boardscharacterized in that waste magnetic tapes of those such as video tapesand cassette tapes are cut or crushed to a proper size, heated, andthen, supplied with a binder and molded under pressure.

In the above-mentioned method of manufacturing building material boards,waste magnetic tapes are cut or crushed to a length of 1 to 50 mm,preferably 3 to 10 mm. Where waste magnetic tapes are crushed to lessthan 1 mm, the cost of crushing is too expensive, and resulting productsbecome powdery, so that a structure holding voids therein is notobtained. For more than 50 mm, the surface state of the products afterbeing molded becomes rough and a lower strength is obtained, therebyproviding no practicability.

The heating treatment is performed at a temperature of 100° to 200° C.,preferably 140° to 170° C. At a temperature less than 100° C., the formof curl is not obtained. At a temperature more than 200° C., theproducts are deteriorated due to air oxidation and thus cannot be used.

As the above-mentioned binder, a material capable of being cured andmolded at room temperature or by heating can be used such as latex,liquid rubber, polyethane adhesive, epoxy resin, melamine resin,phenolic type resin and urea resin.

The binder is added to waste magnetic tapes with 3 to 70 parts,preferably 10 to 50 parts by weight of the former to one part of thelatter, and then both are mixed uniformly.

In manufacturing the above-mentioned building material boards, ferrite,carbon black, graphite, carbon fiber or conductive metallic powderhaving electromagnetic wave properties can be added to waste magnetictapes, or conductive metallic fiber or conductive metallic wire meshhaving a 12 to 100 mesh size can be mixed therein, for example, in asandwich construction.

The above-mentioned ferrite includes spinel based one, garnet based oneand magnet prumbite based one, which are individually or mixedly addedto waste magnetic tapes with 100 to 150 parts, preferably 30 to 70 partsby weight of the former to one part of the latter.

As the above-mentioned carbon black, there can be used channel black,furnace black, acetylene black, thermal black, lamp black and the like,one of which is added to waste magnetic tapes with 1 to 100 parts,preferably 10 to 30 parts by weight of the former to one part of thelatter.

As the above-mentioned conductive metallic powder, iron, stainless,copper, aluminum and the like can be individually used or mixed withcarbon black, which are added to waste magnetic tapes with 10 to 150parts, preferably 30 to 70 parts by weight of the former to one part ofthe latter.

As the above-mentioned conductive metallic fiber or conductive wiremesh, there can be used fiber of iron, stainless, copper, aluminum andthe like, or wire mesh knitted from these fiber and having a 12 to 100mesh size, which are mixed into waste magnetic tapes with 1 to 100parts, preferably 10 to 30 parts by weight of the former to one part ofthe latter.

According to the present invention, waste magnetic tapes of those suchas video tapes and cassette tapes are cut or crushed to a proper size.

To perform cutting or crushing, there can be used an impact type crusherhaving common fixed blades and rotting blades, for example, shown inFIG. 1.

In the figure, numeral 1 designates a hopper; 2, a rotting blade; 3, afixed blade; 4, a screen; and 5, a crusher body.

Waste magnetic tapes are crumpled into a ball and placed from the hopper1, and cut and crushed by the rotting blades 2 and the fixed blades 3.

The size of crushed (or cut) products can be arbitrarily selected bysetting crushing conditions and the size of the mesh of the screen 4.

For example, the products to be crushed used for an experiment arecrushed according to the following distribution in size:

    ______________________________________                                               More than 5 mm  1%                                                            3 to 5 mm       40%                                                           Less than 3 mm  59%                                                    ______________________________________                                    

The above-mentioned products to be crushed, when heated underpredetermined conditions, become crushed products including small pieceswhich have been contracted in the form of curl as shown in FIGS. 2A and2B.

The building material boards of the present invention can be obtained byadding the binder as described above to the crushed products thusobtained, and by molding them under pressure so that they exhibit aproper density.

According to the method of treating waste magnetic tapes of the presentinvention, contracted pieces in the form of curl are obtained, which canbe used not only for the material of the building material boards of thepresent invention, but also for, for example, a filler mixed intocoating film, and the like.

Also, according to the method of manufacturing building material boards,there are obtained building material boards in which air is confinedinto the curl-shaped constracted pieces and thus voids exist, and whichare excellent in sound absorbing and heat insulation performance, aswell as static electricity preventive performance and electromagneticwave absorbing performance, by adding the above-mentioned binder to theabove-mentioned crushed products and molding them under pressure.

The building material boards of the present invention can be used as,for example, the wall, ceiling and floor of buildings, and since theyhave electromagnetic wave properties, they can be preferably used as anelectromagnetic wave shield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a principal portion sectional and elevational view showing anexample of a crusher used in the present invention.

FIGS. 2A and 2B are illustrative views of curl-shaped contracted piecesof waste magnetic tapes formed by the treating method of the presentinvention. Best and Other Modes for Carrying Out the Invention

MODES OF CARRYING OUT THE INVENTION

Embodiments will be shown below, the following commodities were used asa binder:

1) Idemitsu Chemical Co., Ltd.: Modified liquid polybutadiene MC-50

2) Sumitomo Chemical Co., Ltd.: Urethane adhesive Sumistar-9902X

3) Sumitomo Dures Co., Ltd.: phenolic type resin liquid Resin PR-50404

[Embodiment 1]

In the crusher shown in FIG. 1, waste magnetic tapes of cassette tapeswere crushed to scaly pieces with a size of 5 mm or less. They wereheated in an electric furnace heated to a temperature of 150°±5° C. forthree minutes while being agitated, and those having contracted toexhibit a curl shape were used as a raw material, mixed uniformly in aHensil mixer in the following blending ratio, placed into a transfertype mold, and heated under pressure at a temperature of 150° C. for 10minutes in a hot press to mold.

    ______________________________________                                        (Blending)                                                                    ______________________________________                                        Waste magnetic tapes heated:                                                                       100 parts by weight                                      Moisture setting type liquid                                                                       20 parts by weight                                       modified polybutadiene:                                                       Total                120 parts by weight                                      ______________________________________                                    

The physical properties of the building material boards thus obtainedare as follows:

The damping factor in sound absorbing performance was measured by thefalling ball floor impact test (measured by us).

    ______________________________________                                        Density         0.45        g/cm.sup.3                                        Compressive strength                                                                          8.0         kg/cm.sup.2                                       Bending strength                                                                              13.4        kg/cm.sup.2                                       Heat conductivity                                                                             0.043       kcal/m °C. h                               Attenuation in sound                                                                          30          dB                                                absorbing performance                                                         Volume resistance                                                                             <1 × 10.sup.9                                                                       Ω-cm                                        ______________________________________                                    

By changing both the blending ratio of raw material to binder, and thekind of binders, building material boards were manufactures as shown inthe following embodiments 2 through 5, and the physical propertiesthereof were evaluated.

[Embodiment

    ______________________________________                                        (Blending)                                                                    Waste magnetic tapes heated:                                                                   100        parts by weight                                   Spinel based ferrite:                                                                          50         parts by weight                                   Moisture setting type liquid                                                                   30         parts by weight                                   modified polybutadiene:                                                       Total            180        parts by weight                                   (Physical properties)                                                         Density          0.48       g/cm.sup.3                                        Compressive strength                                                                           6.5        kg/cm.sup.3                                       Bending strength 11.1       kg/cm.sup.2                                       Heat conductivity                                                                              0.046      kcal/m °C. h                               Attenuation in sound                                                                           29         dB                                                absorbing performance                                                         Volume resistance                                                                              3.1 × 10.sup.8                                                                     Ω-cm                                        ______________________________________                                    

[Embodiment

    ______________________________________                                        (Blending)                                                                    Waste magnetic tapes heated:                                                                   100        parts by weight                                   Acetylene carbon black:                                                                        20         parts by weight                                   Moisture setting type                                                                          30         parts by weight                                   polyurethane adhesive                                                         Total            150        parts by weight                                   (Physical properties)                                                         Density          0.44       g/cm.sup.3                                        Compressive strength                                                                           7.5        kg/cm.sup.2                                       Bending strength 13.0       kg/cm.sup.2                                       Heat conductivity                                                                              0.041      kcal/m °C. h                               Attenuation in sound                                                                           30         dB                                                absorbing performance                                                         Volume resistance                                                                              5.99 × 10.sup.6                                                                    Ω-cm                                        ______________________________________                                    

[Embodiment

    ______________________________________                                        (Blending)                                                                    Waste magnetic tapes heated:                                                                   100        parts by weight                                   Acetylene carbon black:                                                                        20         parts by weight                                   Stainless powder:                                                                              60         parts by weight                                   Moisture setting type                                                                          40         parts by weight                                   polyurethane adhesive                                                         Total            220        parts by weight                                   (Physical properties)                                                         Density          0.55       g/cm.sup.3                                        Compressive strength                                                                           9.1        kg/cm.sup.2                                       Bending strength 11.6       kg/cm.sup.2                                       Heat conductivity                                                                              0.048      kcal/m °C. h                               Attenuation in sound                                                                           26         dB                                                absorbing performance                                                         Volume resistance                                                                              2.99 × 10.sup.7                                                                    Ω-cm                                        ______________________________________                                    

[Embodiment

    ______________________________________                                        (Blending)                                                                    Waste magnetic tapes heated:                                                                   100        parts by weight                                   Phenolic type resin:                                                                           30         parts by weight                                   Total            130        parts by weight                                   (Physical properties)                                                         Density          0.045      g/cm.sup.3                                        Compressive strength                                                                           8.7        kg/cm.sup.2                                       Bending strength 14.3       kg/cm.sup.2                                       Heat conductivity                                                                              0.043      kcal/m °C. h                               Attenuation in sound                                                                           30         dB                                                absorbing performance                                                         Volume resistance                                                                              <1 × 10.sup.9                                                                      Ω-cm                                        ______________________________________                                    

The boards obtained in the embodiments 1 through 5 were those, forexample, of 10 mm in thickness, 400 mm in depth and 400 mm in width.

Industrial Applicability

According to the present invention, waste magnetic tapes can beeffectively utilized.

According to the method of treating waste magnetic tapes, curl-shapedcontracted pieces are obtained, so that they can be effectively used as,for example, a raw material for manufacturing building material boards,a filler for being mixed into coating film, and the like.

Also, the building material boards obtained by the method ofmanufacturing building material boards of the present invention havevoids, in which air is confined, therein, so that they are excellent insound absorbing and heat insulation performance, as well as staticelectricity preventive performance. Further, waste magnetic tapes areused as raw manufacturing material, so that they are excellent inelectromagnetic wave absorbing performance.

What is claimed is:
 1. A method for treating waste magnetic tapescomprising cutting or crushing said waste magnetic tapes into pieceshaving a length of from 1 mm to 50 mm and heating said pieces to atemperature of from 100° C. to 200° C. so that said pieces contract intoa curled form.
 2. The method for treating waste magnetic tapes accordingto claim 1, wherein said waste magnetic tapes are obtained from videotapes or cassette tapes.
 3. The method for treating waste magnetic tapesaccording to claim 1, wherein said heating occurs in an electricfurnace.
 4. The method for treating waste magnetic tapes according toclaim 1, wherein the temperature is in the range of 140° to 200° C.
 5. Amethod for manufacturing a building material board from waste magnetictapes comprising cutting or crushing said waste magnetic tapes intopieces of a proper size, heating said pieces so that they contract intoa curled form, mixing them with a binder to form a mixture and moldingthe mixture under pressure.
 6. The method for manufacturing a buildingmaterial board according to claim 5, wherein said waste magnetic tapesare obtained from video tapes or cassette tapes.
 7. The method formanufacturing a building material board according to claim 5, whereinsaid proper size is from 1 mm to 50 mm in length.
 8. The method formanufacturing a building material board according to claim 5, whereinthe temperature of said heating is from to 100° C. to 200° C.
 9. Themethod for manufacturing a building material board according to claim 5,wherein said proper size is from 1 mm to 50 mm in length and thetemperature of said heating is from 100° C. to 200° C.
 10. The methodfor manufacturing a building material board according to claim 5,wherein said binder is a material that is moldable and curable at roomtemperature or is a material that is moldable and curable by heating.11. The method for manufacturing a building material board according toclaim 5, wherein said proper size is from 1 mm to 50 mm in length, thetemperature of said heating is from 100° C. to 200° C., and said binderis a material that is moldable and curable at room temperature or is amaterial that is moldable and curable by heating.
 12. The method formanufacturing a building material board according to any one of claims 5to 11, wherein said binder is latex, liquid rubber, a polyurethaneadhesive, an epoxy resin, a melamine resin, a phenolic-type resin or aurea resin.
 13. The method for manufacturing a building material boardaccording to any one of claims 5 to 11, wherein said binder is added tosaid pieces of waste magnetic tape in an amount of from 3 to 70 parts byweight of said binder to 100 parts by weight of said pieces.
 14. Themethod of manufacturing a building material board according to claim 13,wherein said waste magnetic tapes are obtained from video tapes orcassette tapes.
 15. The method for manufacturing a building materialboard according to claim 13, further comprising adding a substancehaving electromagnetic wave properties which is selected from the groupconsisting of ferrite, carbon black, a conductive metallic powder, aconductive metallic fiber, and a conductive metallic wire mesh having amesh size of from 12 to 100, prior to mixing.
 16. The method formanufacturing a building material board according to claim 12, whereinsaid binder is added to said pieces of waste magnetic tape in an amountof from 3 to 70 parts by weight of said binder to 100 parts by weight ofsaid pieces.
 17. The method for manufacturing a building material boardaccording to claim 14, further comprising adding a substance havingelectromagnetic wave properties which is selected from the groupconsisting of ferrite, carbon black, a conductive metallic powder, aconductive metallic fiber, and a conductive metallic wire mesh having amesh size of from 12 to 100, prior to mixing.